Calling stored procredure from psycopg2

Environment is Mageia 5 x86_64, Python 3.4, Postgresql 9.3.20, 
psycopg2-2.7.1

I have a working application that calls an external sql stored procedure 
called search.sql with entry point "search_columns". I access it with 
the statement self.cursor.callproc('search_columns', (target,))

I have moved that application to the following environment: Mageia 6 
x86_64, Python 3.5, Postgresql 9.6.6, psycopg2-2.7.3.2. I now get an 
error message:

psycopg2.ProgrammingError: function search_columns(unknown) does not exist

search.sql is in the same directory as other Python modules, so there 
seems to have been a change in how to call stored sql procedures. Can 
someone help please?

Thanks

Graeme